1. Field of the Invention
The present invention relates to a method and an apparatus for photographing radiation images by using a radiation detection cassette comprising an image memory and a solid-state radiation detector, and also to the radiation detection cassette used therefor.
2. Description of the Related Art
In today""s radiography aimed at medical diagnoses or the like, radiation image photographing apparatuses using solid-state radiation detectors (whose main part comprises semiconductors; hereinafter, simply called a xe2x80x9cdetectorxe2x80x9d or a xe2x80x9cradiation detectorxe2x80x9d in some cases) for outputting an image signal by detecting radiation have been known. As the solid-state radiation detectors used therein, various types have been proposed and put into practice.
With respect to an electric charge generating process in which radiation is converted into an electric charge, solid-state radiation detectors of different types, such as optical conversion type detectors (see Japanese Unexamined Patent Publication Nos. 59(1984)-211263 and 2(1990)-164067, PCT International Publication No. WO92/06501, and SPIE Vol. 1443 Medical Imaging V; Image Physics (1991), p. 108-119, for example) and direct conversion type detectors (MATERIAL PARAMETERS IN THICK HYDROGENATED AMORPHOUS SILICON RADIATION DETECTORS, Lawrence Berkeley Laboratory, University of California, Berkeley, Calif. 94720 Xerox Parc. Palo Alto, Calif. 94304, Metal/Amorphous Silicon Multilayer Radiation Detectors, IEEE TRANSACTIONS ON NUCLEAR SCIENCE. VOL. 36. NO.2. APRIL 1989, and Japanese Unexamined Patent Publication No. 1(1989)-216290, for example), have been known. In an optical conversion type detector, light emitted from a phosphor by exposing the phosphor to radiation is detected by a photoelectric conversion device and a signal charge thereby obtained is stored in a capacitor of the device. The stored electric charge is then converted into an image signal (electrical signal) and the signal is output. In a direct conversion type detector, a signal charge generated within a radiation conductive material by exposing the material to radiation is collected by an electric charge collecting electrode and stored in a capacitor. The stored electric charge is then converted into an electrical signal and the signal is output.
With respect to an electric charge reading process in which a stored electric charge is read out, solid-state radiation detectors of other types, such as TFT reading type detectors which read the charge by scanning TFT""s (Thin Film Transistors) connected to capacitors and optical reading type detectors in which a charge is read by irradiation of reading light (an electromagnetic wave for reading) thereon have been known.
The present assignee has proposed radiation detectors of improved direct conversion type (see Japanese Patent Application Nos. 10(1998)-232824 and 10(1998)-271374). A radiation detector of improved direct conversion type means a radiation detector employing both the direct conversion method and the optical reading method. The radiation detector of improved direct conversion type comprises a first conductive layer which is transparent to radiation for recording, a photoconductive layer for recording exhibiting photoconductivity (or radiation conductivity, more accurately) when receiving the radiation for recording which has passed through the first conductive layer, an electric charge transport layer which acts as an insulator to an electric charge having the same polarity as the electric charge charged in the first conductive layer while acting as a conductor to an electric charge having the reversed polarity, a photoconductive layer for reading presenting photoconductivity (or more accurately, electromagnetic wave conductivity) by receiving an electromagnetic wave for reading, and a second conductive layer which is transparent to the electromagnetic wave for reading, with these layers being stacked in this order. A signal electric charge (latent image electric charge) representing image information is stored at the interface (the capacitor) between the photoconductive layer for recording and the electric charge transport layer. The first and the second conductive layers function as electrodes. The photoconductive layer for recording, the electric charge transport layer, and the photoconductive layer for reading comprise the main part of the solid state detector of this type.
Various kinds of cassette for radiation detection containing in a case a radiation detector and an image memory as recording means for recording an image signal output from the detector have been proposed (for example, see U.S. Pat. Nos. 5661309 and 5773839, and Japanese Unexamined Patent Publication Nos. 6(1994)-342099 and 7(1995)-140255). The cassette described in U.S. Pat. No. 5661309 uses an image memory having a recording capacity for a plurality of images, and stores image data for one image in the image memory each time the image has been detected.
A radiation image photographing apparatus using this cassette records image data for a plurality of images obtained by successive photographing in the image memory, and reads the data of the images from the image memory to collectively output the image data to a signal processing unit located outside the cassette. In this way, it becomes unnecessary to output (transfer) the image data to the external signal processing unit each time one image is detected (photographed). Therefore, efficient successive photographing becomes possible, and processing time between signal detection and signal processing can be reduced.
Meanwhile, upon photographing a radiation image, a photographer generally carries out photographing in an order determined based on a photographing menu such as patient information and photographing information displayed on an image/information display apparatus (hereinafter, simply called display apparatus) controlling photographing.
In the case where the cassette containing the image memory having recording capacity for a plurality of images is used for photographing, the image data read from the image memory do not correspond to the photographing menu used at the time of obtaining the image data, if photographing is carried out in an order different from the order determined in advance, (that is, if the order of photographing is changed during the successive photographing) and if there is no means for relating the photographing menu and the actual images represented by the image data in the image memory. Therefore, appropriate diagnoses cannot be carried out.
For example, in the case of mass medical examination of people""s chests, it is common practice for subjects to be related to a photographing order in advance and a number of plate indicating the order is provided to each subject. A photographer carries out photographing in accordance with the number plates. If photographing is carried out according to the number plates, the photographed images can be related to the subjects. Otherwise, the photographed images do not correspond to the subjects, which causes a problem on diagnosis. The same problem occurs if the cassette to be used is misplaced.
Furthermore, in the field of recent medical diagnosis, networking has been in progress. A work flow is determined based on a diagnosis of a clinician, and the work flow is transferred to each consulting room via a network. Various kinds of processing are then carried out based on the work flow. A photographing menu is included in the work flow. However, processing may be carried out in a flow different from the work flow, due to convenience of a consulting room. Therefore, the likelihood of carrying out processing procedures different from the predetermined processing procedures is growing.
Therefore, realization of means for properly relating a photographing menu to image data recorded in an image memory has been desired so that no problem occurs even when a procedure different from a predetermined work flow is taken in a network environment.
The present invention has been conceived based on consideration of the above problems. An object of the present invention is to provide a radiation image photographing method and a radiation image photographing apparatus for recording radiation image data representing radiation images in an image memory in a cassette in such a manner that the image data read from the image memory can be related to a photographing menu used at the time of photographing the images, and also a cassette for radiation detection used therefor.
A radiation image photographing method of the present invention uses a radiation detection cassette containing a radiation detector for outputting image data by detecting radiation representing radiation image information obtained by photographing and an image memory for storing the image data output from the radiation detector, and the radiation image photographing method comprises the step of:
storing the image data representing images in the image memory by relating the image data of each image with a photographing menu used at the time of obtaining the image data, via a counter value for counting how many times photographing has been carried out.
The xe2x80x9cphotographing menuxe2x80x9d herein referred to means various conditions affecting a relationship between a radiation dose at the time of photographing and the values of the image data output from the detector. As the photographing menu, a photographing mode (such as normal photographing, enlargement photographing, and tomography), a photographing condition (such as the kind of subject, a tube voltage of an X-ray source, and the radiation dose), a body part to be photographed (such as the head, neck, chest, and abdomen), and a photographing apparatus can be listed. Hereinafter, these conditions are collectively called a photographing menu.
The xe2x80x9ccounter value for counting how many times photographing has been carried outxe2x80x9d can be numbers such as 1, 2, and 3 but also characters or symbols such as A, B, and C, as long as the order of photographing can be. managed thereby. The counter for obtaining the counter value can be located anywhere as long as the counter can manage the order of photographing. For example, the counter may be located on a cassette or in an apparatus other than the cassette, such as a display apparatus. The counter can be of any kind. However, a counter which increases by 1 at each time of photographing (recording image data) is convenient to use. The counter preferably has reset and preset functions.
xe2x80x9cStoring the image data . . . by relating the image data of each image with a photographing menu used at the time of photographingxe2x80x9d means to relate the image data and the photographing menu in such a manner that the photographing menu used at the time of obtaining the image data is known when the image data are read from the image memory. In other words, the image data and the photographing menu have a certain relationship (the image data are linked to the photographing menu). To relate the image data and the menu xe2x80x9cvia a counter valuexe2x80x9d means the counter value mediates the relationship (link) between the image data and the photographing menu. In other words, the counter value is related to the image data while being related to the photographing menu. The image data and the photographing menu may be linked to each other via another item, as long as the counter value also serves as the mediator. For example, a menu code for identifying the photographing menu may be used so that the image data are related to the counter value while the counter value is related to the menu code related to the photographing menu.
xe2x80x9cStoring the image data . . . in the image memory by relating the image data of each image with a photographingxe2x80x9d means any manner of storing, as long as the data of each image are stored in the image memory by being related to the photographing menu via the counter value, as has been described above. For example, the counter value may be stored in the image memory (as accompanying information of the image data, for example), together with the image data. Alternatively, the image data may be stored in a memory address related to the counter value. Furthermore, a table relating the counter value with the image data representing each image may be generated so that only-the image data can be stored in the image memory. When the image data are read, the table having been generated is referred to. It is needless to say that the data of the table may be stored in the image memory so that the data can be read thereafter.
It is preferable for the radiation image photographing method of the present invention to relate an identification code for identifying the radiation detection cassette with the counter value. Any method can be used for relating the identification code with the counter value, as long as the cassette used can be identified at the time the image data are read from the image memory.
A radiation image photographing apparatus of the present invention is an apparatus for realizing the above method. In other words, the radiation image photographing apparatus of the present invention uses a radiation detection cassette containing a radiation detector for outputting image data by detecting radiation representing radiation image information obtained by photographing and an image memory for storing the image data output from the radiation detector, and the radiation image photographing apparatus comprises:
means for storing image data representing a plurality of images in the image memory by relating the image data representing each image with a photographing menu used at the time of obtaining the image data, via a counter value for counting how many times photographing has been carried out.
As this means, any means can be used as long as the image data representing each image are related to the photographing menu via the counter value.
For example, the counter value transferred from the cassette may be related to the photographing menu on a display apparatus controlling photographing. Alternatively, the counter value may be managed on the display apparatus in order to relate the counter value with the photographing menu, while the counter value is transferred to the cassette so that the image memory within the cassette stores the image data by relating the counter value having been transferred with the image data. The transfer of the counter value may be carried out by using either a wired or wireless system.
It is preferable for the radiation image photographing apparatus of the present invention to comprise means for relating an identification code for identifying the radiation detection cassette with the counter value.
As the means for relating the identification code with the cassette, any means can be adopted as long as the counter value is related to the identification code so that the cassette used can be identified. For example, the identification code may be recorded in the image memory together with the image data, or the identification code may be referred to when the image data are read.
The radiation detection cassette of the present invention is used in the radiation image photographing method and apparatus described above. In other words, the cassette contains a radiation detector for outputting image data by detecting radiation representing radiation image information obtained by photographing and an image memory for storing the image data output from the radiation detector, and the image memory stores:
the image data representing a plurality of images by relating the image data with a photographing menu used at the time of obtaining the image data representing each image, via a counter value for counting how many times photographing has been carried out.
It is preferable for the image memory to record an identification code for identifying the cassette.
As the radiation detector contained within the radiation detection cassette of the present invention, radiation detectors of various types described above can be used. However, the present invention is not limited to the above example, and any solid-state radiation detector can be used as long as the radiation detector includes solid-state detection devices aligned with each other and each comprising a semiconductor for detecting radiation as a main part thereof.
According to the radiation image photographing method and apparatus and the radiation detection cassette of the present invention, the image data representing each image are stored in the image memory by being related to the photographing menu used at the time of obtaining the image data, via the counter value for counting how many times photographing has been carried out. Therefore, even if an image memory having sufficient capacity to record a plurality of images is used, the photographing menu can be properly related to the image data representing each image. As a result, even if photographing is carried out in an order different from a predetermined order, the relationship between the menu and the image data can be established and the photographing menu can be properly related to actual images represented by the image signals stored in the image memory.
Furthermore, if the identification code for identifying a cassette is related to the counter value, which cassette has been used can be known easily, and the photographing menu can be accurately related to the image data even if a cassette different from a predetermined cassette has been used.